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Overdoor Heating

The vocabulary used to describe heaters designed to be installed over doors can be very confusing.  The terms air curtain, screen heater, overdoor heater etc. are bandied about and seem to mean completely different things to different people.

Our main purpose here is to differentiate between two products both which have a useful but distinctly different purpose.

Overdoor Heaters

Overdoor heaters are widely used in shops and can be wall-mounted, suspended or recessed into the ceiling above standard height doors.  They provide a warm welcome to customers and a localised boost to the air temperature, offsetting the heat loss associated with frequently opening doors.  BN Thermic’s 800 Series is ideal for this application.  The 800 Series extends from a 3kW model best suited to a single door to 6kW and 9kW models for wider entrances. 

All 800 series heaters come with a bracket for wall-mounting and also have threaded holes for drop rod suspension where this installation method is preferred.  A remote mounted control box provides on/off/high heat/low heat/fan only settings.

>>Full details of BN Thermic’s 800 Series Air Curtains

860 ofs
adjustable room thermostat 16A (3)

Black Over Door Heaters

To adapt to more modern building aesthetics, BN Thermic have introduced a new range of 3, 6 and 9kW overdoor heaters in a sleek black finish. Like their counterparts in a white finish, these units are UK assembled and can be easily controlled via a CS-7 switch.

All 800 series heaters in a black finish have a ‘B’ suffix at the end of their product code.

Commercial Air Curtains

BN Thermic’s CA commercial air curtain range is better suited to businesses with a more open door policy. This includes applications such as hotel foyers, larger shops, office entrances and restaurants. The CA range mirrors the kW outputs and dimensions of an 800 series range but CA air curtains have a higher m3/h air flow rate. This means they create a more effective barrier and subsequently limit heat loss.

Like the 800 series, all CA air curtains come with mounting bracket as standard and can be controlled remotely by the CS-7 switch. 

air curtain

SystemX – Multi Heater Installs

BN Thermic’s SystemX range allows you to daisy chain multiple heaters and control them via one controller. All control connections are made with CAT5 cable making it incredibly quick to install.

The CA and 800 series ranges are available in a SystemX version with product codes starting XD and XA respectively. This allows you to install multiple overdoor heaters/air curtains and link them to a single controller – ideal for shops with an entrance and an exit next to each other. By using SystemX on these types of installs, installation costs and time can be slashed.

Selecting the Right Overdoor Heater or Air Curtain 

Selecting the right overdoor heater or air curtain is very important and can be tricky. For help with product selection, BN Thermic’s engineers are a call away. All they require is the width and height of your door and an idea of the environment the unit is going into.

The below diagram will also assist you in making a decision. 

overdoor and systemx

Over Door Heater FAQs & Guide

  • An overdoor heater (often referred to as an over door heater or simply a door heater) is a linear fan heater positioned above a door.  It produces a relatively low velocity air stream that blows down across the doorway.  

    Electrically heated overdoor heaters (such as those manufactured by BN Thermic) incorporate electric heating elements which heat the moving air to a pleasantly warm temperature.

    Frequently used in shops, cafes and restaurants, overdoor heaters provide a warm welcome for customers and localised heating at a point of high heat loss.  Overdoor heaters also mitigate against cold draughts.

  • An air curtain is a linear device installed above a door.  Its primary function is to produce a stream of air across an open doorway creating an invisible barrier and, in doing so, limiting the loss of warm air.  

    Some air curtains offer no heating whatsoever and these are generally known as ambient air curtains.  However, an unheated, high velocity air stream induces a very noticeable cooling effect which can be uncomfortable for people in the vicinity.  For this reason, most air curtains are supplied with either built-in electric heating elements or hot water coils.

  • An overdoor heater (often referred to as an over door heater or simply a door heater) and an air curtain are similar in that they are both positioned above a door and produce a stream of air directed downwards towards the floor.

    The difference is the velocity of the air stream.  Overdoor heaters produce a relatively low velocity air stream when compared to a similarly sized air curtain.  The implications of this difference are as follows.

    • Comparing units with the same kW output, an overdoor heater will produce an air stream that feels warmer
    • An overdoor heater will be quieter than a similarly sized air curtain
    • An overdoor heater will not be as effective at producing an invisible barrier across an open doorway as an air curtain and, therefore, will not be as efficient in limiting the loss of warn air from a heated building
  • An air curtain reduces heating bills by creating an invisible air barrier across a doorway and preventing heated air from escaping.  Higher velocity air curtains will produce a more effective barrier and be suitable for a higher mounting position but will produce more noise than a lower velocity equivalent.  Higher velocity air curtains will also need a higher output heater to achieve an acceptable air stream temperature resulting in somewhat higher running costs.

    BN Thermic offers two types of air curtain.

    High capacity air curtains are ideally suited to larger commercial and industrial premises such as superstores and large-scale reception areas.

    Commercial air curtains are better suited to convenience stores, small-scale reception areas and lobbies etc.